The present invention relates to a method for supplying and discharging gas to and from a semiconductor manufacturing equipment and a system for executing such method.
Description is given to the prior art, referring to FIG. 19, which represents a type of semiconductor manufacturing equipment, i.e. a vertical diffusion/CVD system provided with a load-lock chamber.
In a reaction chamber 1, which also serves an airtight chamber and a processing chamber, an airtight load-lock chamber 3 is arranged through a gate valve 2, and a nitrogen gas supply line 4 and a gas discharge line 5 are connected to the reaction chamber 1. Also, a nitrogen gas supply line 6, a gas discharge line 7 and a vacuum pump 8 are connected to the load-lock chamber 3. An air valve 9 is connected to the nitrogen gas supply line, and an air valve 10 to the gas discharge line 7.
The load-lock chamber 3 is provided with a boat inserting device (not shown), which inserts a wafer 12 loaded on a boat 11 into the reaction chamber 1, performs processings such as diffusion, thin film deposition, etc. and takes it out thereafter.
Describing gas supplying and discharging operation in this conventional type vertical diffusion/CVD system, the vacuum pump 8 is driven with the gate valve 2 closed to turn the load-lock chamber 3 to vacuum condition. Then, nitrogen gas is introduced through the nitrogen gas supply line 6 to produce nitrogen gas atmosphere in the load-lock chamber 3 and to reduce oxygen concentration there.
In the conventional type vertical diffusion/CVD system as described above, when nitrogen gas is introduced and the load-lock chamber 3 is turned to nitrogen gas atmosphere, the load-lock chamber 3 is under positive pressure, and pressure difference from the reaction chamber 1 occurs. As the result, when the gate valve 2 is opened, the nitrogen gas flows into the reaction chamber 1 from the load-lock chamber 3 due to the pressure difference, and this induces dusting. Thus, particles increase in the reaction chamber 1 and the load-lock chamber 3, and cleanliness level of the wafer 12 is decreased.
To solve the above problems, it is an object of the present invention to provide a semiconductor manufacturing equipment comprising a vertical diffusion/CVD system, by which it is possible to prevent dusting when the gate valve 2 is opened.